The present invention generally relates to a mobile communication network system and a mobility managing unit for managing mobility of a mobile node when handing-over.
Nowadays, research is being conducted relating to the next generation mobile communication network for “Beyond IMT-2000” after the third generation mobile communications. It is believed that the next generation mobile communications needs a network in which multimedia traffic and audio traffic can be effectively processed by IP (Internet Protocol) based network processing. A subject for mobile communication service is not only human but also all kinds of moving objects such as automobiles, bicycles, pets, parcels, etc. Therefore, how to effectively realize mobility management is becoming important.
In general mobile communication network systems, location information of a mobile node (MN) is managed by a mobility managing unit (RM: Routing Manager). When the mobile node moves over base stations and should be handed-over, the mobile node registers its location in this RM to control hand-over of the mobile node.
On the other hand, according to a technology described in Non-patent Document #1, for a mobile node (MN), an HRM (Home Routing Manager) to which the MN belongs and an LRM (Local Routing Manager) are defined and these two mangers manage the MN mobility. The LRM has a function for managing location information of the MN within a certain area and a function for managing a CN (Correspondent Node), and the HRM has a function for managing the location of a network in which the mobile node is located.
In this type of network, in order that the MN moves and continues to communicate with the CN even after connecting to a new neighbor base station, the new base station needs to revise a cache table (CST: Cache for Source Terminal) indicating the location information of the MN in the network within which the MN is located, and reset a cache table (CDT: Cache for Destination Terminal) indicating the location information of the CN. This resetting is performed by the base station asking the LRM.
When the MN continues to move, it may go beyond the area managed by the present LRM and move to an area managed by a neighbor LRM (hand-over beyond LRM). Even when handing-over beyond LRM, the base station asks a new LRM about CDT, but the new LRM does not have CDT information.
In the third generation IMT-2000 mobile communication network, the MN transmits information of the old LRM to a new LRM after handing-over, and the new LRM asks the old LRM for the information. If this technique is applied to the present technical field, the MN transmits the old LRM information to a new LRM, and the new LRM asks the old LRM for the CDT information.
In the IMT-2000 mobile communication network, forwarded information is a user profile, which is not related to hand-over control. However, in the present technical field, the LRM directly controls hand-over, and if the CDT information is not forwarded, then the hand-over control is not completed.